Process for making a false twisted differential tension yarn

Abstract

A continuous multifilament crimped polyamide or polypropylene yarn suitable for use in loop pile carpeting and the process for making the yarn including feeding the yarn at different tensions and then treating the yarn with saturated steam is disclosed.

I claim: 
     
       1. A process for making a continuous multifilament crimped polyamide yarn suitable for use in loop pile carpeting comprising the steps of: (a) combining at least two multifilament crimped polyamide yarns at different tensions such that the yarns are not overwrapped and feeding such combined yarns through a heating zone in a false-twisted state;   (b) heating the false-twisted yarns with saturated steam; and   (c) false-twisting the yarns.   
     
     
       2. A process for making a continuous multifilament crimped polypropylene yarn suitable for use in loop pile carpeting comprising the steps of: (a) combining at least two multifilament crimped polypropylene yarns at different tensions such that the yarns are not overwrapped and feeding such combined yarns through a heating zone in a false-twisted state;   (b) heating the false-twisted yarns with saturated steam; and   (c) false-twisting the yarns.   
     
     
       3. The process of claim 1 or 2 wherein the tension on at least one of the higher tensioned yarns of the multifilament crimped yarns is about 0.02-0.25 gpd and the tension on at least one of the other lower tensioned multifilament crimped yarns is about 0.008-0.16 gpd and the lower tensioned yarn is 0.012-0.16 gpd lower tension than the higher tensioned yarn. 
     
     
       4. The process of claim 3 wherein the yarns are false-twisted in a torque jet. 
     
     
       5. The process of claim 4 wherein the saturated steam is substantially free from entrained water. 
     
     
       6. The process of claim 5 further comprising the step of winding the yarn wherein the wind-up speed is greater than 200 ypm (183 mpm). 
     
     
       7. The process of claim 5 wherein the angle between the lower tensioned and the higher tensioned yarn at which the yarns meet is at least about 10°. 
     
     
       8. The process of claim 6 wherein the tension on at least one of the higher tensioned yarns of the multifilament crimped yarns is about 0.04-0.16 gpd and the lower tensioned yarn is 0.032-0.10 gpd lower tension than the higher tensioned yarn.